Continuing research in physics has revealed fewer, rather than more, natural laws. The author, a mathematical physicist specializing in particles and their forces, shows this to be the case in this splendid survey of physics, mainly since the time of Galileo. In the Preface he explains that one theme of this "non-technical tour through the principles of physics" is "that progress has often consisted in uncovering 'hidden unities.' . . . Every time such a unification is achieved, the number of 'laws of nature' is reduced, so that nature looks not only more unified but also, in some sense, simpler. More and more apparently diverse phenomena are explained by fewer and fewer underlying principles" (p. xi). The book's second theme arises because "Quite often, different branches of physics have seemed to contradict each other when taken together. The contradiction is then resolved in a new, more consistent, wider theory, which includes the two branches" (ibid.), such as the conflict between electromagnetism and Newton's theories of motion and gravitation being resolved by Einstein's relativity theories.

Organized partially chronologically, the book covers topics ranging from motion, heat, electromagnetism, and light, to space, time, and quantum and particle physics, with two-thirds of the book concentrating on 20th-century issues. Along the way it describes in an intriguing way the contributions of some of the prominent scientists whose work still has contemporary value. Concepts are explained largely through words and diagrams rather than mathematical notation, which the author feels is appropriate since "mathematical symbols can never be the whole story. You can write down as many elegant equations as you like, but somewhere there has to be a framework for connecting these symbols to real things in the world. To provide this, I do not think there is any substitute for ordinary language" (p. xii). -- I. M. Oderberg